In colonoscopy or bowel surgery, the colon must be preliminarily emptied through bowel cleansing, which involves administration of a bowel-cleansing agent. Hitherto, an electrolyte solution containing polyethylene glycol (PEG electrolyte solution) or diluted magnesium citrate solution (i.e., large volume magnesium citrate method) has been employed as a bowel-cleansing agent. Since PEG electrolyte solution and diluted magnesium citrate solution are liquid agents and have poor flavor, etc., patients encounter difficulty in taking such a liquid agent, which problematically reduces compliance.
In recent years, in order to solve the aforementioned problems, solid bowel-cleansing agents such as tablet-form agents have been developed. The thus-developed solid agents, which are readily taken by subjects, are widely employed in bowel cleansing. Examples of the solid bowel-cleansing agent include a tablet-form agent containing sodium phosphate as an effective ingredient and granules containing as effective ingredients sodium chloride, potassium chloride, sodium bicarbonate, and sodium sulfate. In the case of granules containing a potassium salt, an adverse effect such as hyperpotassemia occurs due to excessive absorption of potassium by a subject, which is problematic. In contrast, since the tablet-form agent contains sodium phosphate as an effective ingredient, the agent causes less adverse effects and is readily taken by a subject, which is advantageous.
In order to reduce the size of the sodium phosphate-containing tablet-form bowel-cleansing agent and ensure moderate dissolution property, crystalline cellulose is incorporated into the agent as an excipient. However, crystalline cellulose often remains in the intestinal tract due to insolubility in water, and the remaining cellulose must be removed through, for example, suction or washing upon colonoscopy, which is problematic.
Meanwhile, it has been reported that polyethylene glycol, which is a water-soluble binder, is added to the sodium phosphate-containing tablet-form bowel-cleansing agent (Patent Document 1). However, dissolution of an ingredient of a tablet containing polyethylene glycol is considerably rapid, which may cause adverse effects. In fact, such an agent has not yet been put on the market in Japan. Furthermore, for fully attaining the binding function of polyethylene glycol, the production thereof preferably includes a heating step. In this case, the water content of raw material must be carefully regulated. In addition, for sufficiently dispersing the binder and uniformly heating polyethylene glycol, the production thereof often requires discontinuous batch treatments.